HORSES AND MULES 



579 



Fig. 1. — At one year of age the 

 jaw is narrow, the temporary teeth 

 are small and the corner incisors are 

 not yet in contact. 



Fig. 2. — At two years of 

 age the jaw shows greater width 

 than at one year of age, and the 

 teeth are all in contact and show 

 considerable wear. 



Fig. 3. — At three years of 

 age the permanent incisors above 

 and below are in wear. Note the 

 greater width and length in com- 

 parison to the temporary teeth. 



Fig. 4. — At four years 

 of age the permanent and in- 

 termediate incisors on lower 

 and upper jaws are in wear. 

 The corner pair of temporary 

 teeth have not been dis- 

 placed; they appear very 

 small in comparison with the 

 permanent teeth. 



1 .Ac ■*- Teu* Y£1*s 



Note. — Photographs showing teeth at various ages, by courtesy of Prof. S. T. 

 Simpson, Agricultural Extension Service, Missouri Experiment Station. 



